The Characteristic of TMG adsorption on the Si(100)(2×1) surface in atomic layer deposition (ALD): Computational prediction of Si9H12O2GaCH3 structure

P. PUNGBOON PANSILA, Poramate Chunpang, Seckson Sukhasena


This work reports the adsorption characteristic of trimethylgallium (TMG) on the silicon surface in the adsorption step of atomic layer deposition (ALD) to prepare gallium oxide thin film by using TMG as the gallium source.  One dimer Si(100)(2×1) is employed as the substrate for the TMG adsorption, since the surface hydroxyls are utilized as the absorption sites. TMG is predicted to consume the two sites adsorption on the top surface of silicon substrate. The adsorption characteristic on the silicon surface and the molecule vibrations are calculated by Gaussian09 package for standard method with B3LYP/6-311G**. The adsorption pressure is controlled at the constant of 8.6×10-3 torr, while the process temperatures are varied.  The Gibbs free energy value is used to consider as self-adsorption on the silicon substrate. The results showed that TMG is possible to adsorb on the silicon surface with two sites adsorption as the Si9H12O2GaCH3 structure at the process temperature is rising to ~266.14 °C. Besides that, the adsorption characteristic and the vibrational frequencies of Si9H12O2GaCH3 surface structure are also reported in this paper.

 Keywords: Atomic layer deposition (ALD), TMG adsorption, Si(100)(2×1), Gallium oxide, Computational method

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